1. Field of the Invention
The present invention relates to an image-pickup apparatus that performs focal-point detection by using an image-pickup element that performs image pickup for performing finder display. Further, the present invention relates to a control method applied to the image-pickup apparatus and to a control program for operating a computer used for the image-pickup apparatus.
2. Description of the Related Art
The art of using images picked up by a CCD video camera as AF images for performing mountain-climbing AF and as EVF images to be displayed on an electronic viewfinder (an EVF) is disclosed in Japanese Patent Laid-Open No. 7-143388.
The art of splitting part of an image-pickup element of a digital camera in two for performing phase-difference AF (autofocus) is disclosed in Japanese Patent Laid-Open No. 2000-305010. In such a case, it becomes possible to calculate the direction of a subject (the driving direction of a lens) and the moving amount of the lens more appropriately than in the case where the mountain-climbing AF is performed.
However, the above-described arts have the following problems.
In the case where the mountain-climbing AF as in Japanese Patent Laid-Open No. 7-143388 is performed, the contrast peak of subject images is searched by moving the lens. Therefore, it becomes necessary to perform AF calculation for each field by using image data. Subsequently, the AF speed is decreased.
Further, according to the art disclosed in Japanese Patent Laid-Open No. 2000-305010, the phase-difference AF is performed. Therefore, it becomes possible to calculate the subject direction and the defocusing amount by using an output image data obtained by using only one image pickup. However, the output image data is obtained by using only part of pixels of the image pickup element. Therefore, the obtained image cannot be used as an EVF image. In such a case, an optical finder, which requires expensive parts, such as a mirror, a prism, and so forth, and ample space, is used.
Accordingly, the object of the present invention is to provide an image-pickup apparatus that can perform high-speed autofocusing (AF) by using an electronic viewfinder (EVF), an image-pickup method, a control program, and a recording medium.